This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The primary objective of this proposal is to use the high performance computing (HPC) resources and computational fluid dynamics (CFD) software at SDSC to simulate the airflow and aerosol transport in human airways. There have been extensive evidences linking the exposure to particulate matter in environment to human health. The increasingly awareness of biological warfare and the increasing use of inhalation drug delivery also emphasize the need to better understand the fate of inhaled aerosols in the human lung. In the past a majority of studies on aerosol transport in the human lung have focused on the upper and large airways. Data on alveolated small airways have been very limited, and for those existing studies there are serious limitations such as assumption of rigid wall, 2D geometry, or no bifurcation. Our research group at UCSD has recently developed preliminary state-of-the-art models of three-dimensional, alveolated, and bifurcated airways with compliant walls. Initial simulations using a desktop computer have produced some interesting and important results. However, the computing power of the desktop computer seriously limits the efficient production of realistic and highly significant results. Therefore, we propose to use the computing resources at SDSC to help realize our research objectives. The PI of this proposal has more than three years of extensive knowledge of using CFD software (Fluent) with HPC resources at another supercomputing center, focusing on a related project as the current one. In this project we plan to continue to use Fluent software, which was already installed on SDSC computers and licenses are currently available. In the previous experience with the software very good parallel performance has been observed. Therefore, it is expected that highly efficient use of the computing resources and software and highly significant research results will occur as a result of this proposal.